Concurrent infections of Fasciola, Schistosoma and Amphistomum spp. in cattle from Kafue and Zambezi river basins of Zambia.

This study investigated interactions among Fasciola gigantica, Schistosoma spp. and Amphistomum spp. concurrent natural infections in Zambian cattle, based on egg and worm counts. In the abattoir 315 cattle were screened for worms of F. gigantica in the liver, Schistosoma spp. in mesenteric veins and/or Amphistomum spp. in the rumen. One hundred and thirty-three (42.2%) of the abattoir-examined cattle harboured one, two or all three trematodes. Of 133 cattle, 50 were randomly selected for worm and egg counts. The mean numbers (+/- SD) of Amphistomum, Schistosoma and Fasciola were 622.08 (+/- 97.87), 33.68 (+/- 7.44) and 19.46 (+/- 4.58), respectively. A total of 32% harboured all the three trematodes, 66% had F. gigantica and Amphistomum spp. infections, 52% had Schistosoma spp. and Amphistomum spp. infections while 32% had F. gigantica and Schistosoma infections. A positive correlation (P = 0.014) was found between F. gigantica and Amphistomum worm burdens. There were no correlations between Amphistomum and Schistosoma worm burdens and between F. gigantica and Schistosoma worm burdens. It may be concluded that there is no significant cross-protection among these trematodes in cattle in endemic areas.

Comparative fluke burden and pathology in condemned and non-condemned cattle livers from selected abattoirs in Zambia.

After dissecting 70 condemned and 32 non-condemned cattle livers collected from Lusaka, Chisamba, Mongu and Senanga abattoirs and Turnpike slaughter slab, significantly higher numbers of liver flukes (Fasciola gigantica) (P < 0.001) were found in the condemned livers (mean +/- SD = 100.6 +/- 16.7) than in the non-condemned livers (mean +/- SD = 0.7 +/- 0.5). Liver flukes found in 9.4% of the non-condemned livers suggest that abattoir records of liver inspection may underestimate F. gigantica infections. Average faecal fluke egg counts from animals with condemned livers (5 eggs per gram [EPG]) were significantly higher (P < 0.001) than in animals with non-condemned livers (0.8 EPG). No correlation was found between egg counts and number of flukes. Fibrosis and calcification were common in condemned livers, being severest in the vicinity of the bile ducts. Only two (6.3%) of the non-condemned livers showed pathological changes on the liver edges. The severe liver damage and high worm burden may explain low production levels experienced in cattle in Zambia maintained under traditional systems of management where worm control and good management programmes are rarely practiced.

Seasonal pattern of bovine fasciolosis in the Kafue and Zambezi catchment areas of Zambia.

In order to establish seasonality of bovine fasciolosis in the Southern province of Zambia, 288 cattle were examined at slaughter at Turnpike slaughter slab for 1 year. The examination involved liver inspection and coprological examination. Liver condemnation rates were relatively high at the beginning of both the cold dry season and the rainy season (May/June and December, respectively). All cattle, regardless of age, had higher fluke abundances in the post-rainy season (39.1% young and 42.1% adult) while the lowest rates were in the hot dry season (13.3% young and 14.3% adult). On coprological examination, the highest abundance was in the post-rainy season (45.0%) and the lowest in the cold dry season (24.9%). From November (end of dry season) to February/March (end of rains), more fluke eggs were found than in any other period. The distribution of fluke eggs was significantly different (p<0.001) among the four seasons. Identified associations were: egg counts were highest in post-rainy (mean abundance=146) and lowest in cold dry season (mean abundance=118) at 95% confidence (CI 0.64-1.25). Differences in abundance observed according to origin, sex and age of cattle were not significant on both methods. Based on these results, it may be concluded that Fasciola gigantica was present throughout the year in cattle in Zambia but the abundance was highest in the post-rainy season and lowest in the cold dry season.

The influence of colostrum on infection of calves around 7 months of age with Schistosoma mattheei.

Studies have indicated that the intake of colostrum could modulate the offspring reaction towards early schistosome infections. The effect of colostrum (containing immunoglobulins, parasite antigens, immune cells and other cell-related products) on late Schistosoma infections is to our knowledge not documented. The objective of the present study is to determine whether the intake of colostrum from Schistosoma mattheei infected cows will modify late S. mattheei infection patterns in their offspring. Six calves born to confirmed non-infected cows and 10 calves born to confirmed infected mothers were purchased after intake of colostrum. All calves were exposed to a total experimental challenge of 2500 cercariae around the age of 7 months. Serum samples were collected before and after intake of colostrum and monthly thereafter for the determination of specific antibody levels. Faecal samples were collected monthly from 42 days after infection for the determination of faecal egg counts. Six calves of each group were slaughtered around the age of 15 months for worm recovery and tissue egg counting. No differences between both groups were observed in immunoglobulin levels and faecal egg counts after infection, and in worm counts and tissue egg counts at necropsy. In conclusion colostral effects, which were noticed at an early age, are no longer present around the age of 7 months. As such calves which are born during a season of high Schistosoma transmission will still be under colostral influence and therefore be more protected against a primary challenge than calves born during a low transmission season, as the latter will only receive their first challenge when colostral protective effects have disappeared.